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Transfer of crude oil from contaminated water to bird eggs
ENVIRONMENTAL
RESEARCH
Transfer
22. 307-314 (1980)
of Crude
Oil from Contaminated Bird Eggs
Water to
PETERH. ALBERS
Pairs of breeding mallard ducks were exposed to oiled water for 2 days during the first week of incubation. Hatching success of ducks exposed to 100 ml of Prudhoe Bay crude oil per square meter of water surface was significantly less than that of controls. Hatching success of ducks exposed to 5 ml of crude oil per square meter of water surface was less than that of controls but the difference was not significant. The presence of oil on the eggs of ducks exposed to oiled water was confirmed by chemical analysis. Thermocouple probes were used to monitor the egg and nest temperatures of some of the ducks in each of the three groups. Incubation temperatures of oiled females were not significantly different from those of the controls. The incubation behavior of females exposed to oiled water and the first-week survival of their ducklings was not affected by the oil.
INTRODUCTION
Oil spills frequently result in the oiling of large numbers of aquatic birds. If the spill occurs during the spring, breeding birds are affected and oil may be transferred to the eggs on the feathers or feet of the incubating adults (Rittinghaus, 1956; Birkhead et al.. 1973). Hartung (1965) and King and Lefever (1979) demonstrated that oil applied to the breast feathers of incubating mallards and laughing gulls (Latxs utricilla) could be transferred to the eggs. Severe reductions in egg hatchability were caused by the transferred oil in each of these instances. Crude and refined oils are very toxic to bird embryos, particularly during the first 10 days of incubation. Applications of Southern Louisiana and Kuwait crude oils, No. 2 fuel oil, and Bunker C fuel oil on the egg shell in quantities as small as l-5 liters have significantly decreased the hatchability of artificially incubated mallard (Anus plutyrhynchos) and great black-backed gull (Lurns marks) eggs (Albers, 1977, 1978: Szaro et N/., 1978; Coon ef al., 1979; Szaro, 1979). Applications of 20 ~1 of No. 2 fuel oil on the naturally incubated eggs of common eiders (Somuteriu molfissimu). Louisiana herons (Hylrunussu tricolor), laughing gulls (Laws utriciflu), great black-backed gulls, and sandwich terns (Sterna sundvicensis) also significantly decreased egg hatchability (Albers and Szaro, 1978; White et al., 1979; Coon et al., 1979: McGill and Richmond, 1979). Although oil can be transferred from feathers to eggs (Hartung, 1965: King and Lefever, 1979), it has not been demonstrated experimentally that an incubating bird confronted with oil-contaminated water will enter the water, become oiled, and then transfer that oil to the eggs. Furthermore, the effects of a sublethal exposure to oil on incubation behavior are unknown. Keith (1966) first proposed that environmental contaminants, such as DDT, may affect hatchability through their effect on incubation behavior. Peakall and Peakall (1973) showed that the 307 0013-935
l/80/040307-08$02.00/O
Copyright fe 1980 by Academic Press. Inc. All rights of reproduction in any form recerved.
308
PETER
H.
ALBERS
mean temperature was lower and the variation in nest temperature over a 24-hr period was greater for ring doves (Streptopelia risoria) maintained on a diet containing a PCB (Aroclor 1254) than for control birds. Hatching success for the PCB-fed doves was less than for the controls. Unsuccessful nests of herring gull (Lams argentatus) had greater daily variation in nest air temperatures and poorer nest attentiveness by the incubating bird than successful nests (Fox et al., 1978). Organochlorine compounds and PCBs were thought to be responsible for this abnormal incubation behavior. The assumption that an incubating bird can oil itself from contaminated water and transfer the oil to the eggs in amounts sufficient to significantly reduce egg hatchability was tested in the present study. In addition, the effect of sublethal oiling on several aspects of incubation behavior was evaluated. METHODS
AND MATERIALS
Two-year-old mallard ducks were paired and placed in 54 outdoor pens at the Patuxent Wildlife Research Center, Laurel, Maryland, in early February 1978. Each pen measured 4.6 m long by 4.6 m wide by 1.8 m high and contained a water trough 1.2 m long by 0.9 m wide by 0.3 m deep, a cylindrical wire and tarpaper nest box, a feeder, and an electrical outlet. Each nest box contained a layer of straw on top of a layer of wood shavings. The pens were randomly divided into three groups of 18 pens each. The ducks were fed commercial duck breeder pellets throughout the experiment. The completed clutches of eggs were candled every other day to monitor embryonic development. At a convenient time during the first 10 days of incubation, usually Days 5 or 6, the infertile eggs and eggs with retarded development were removed and the water in the troughs was treated with crude oil. Pens in one group received a “high” treatment of 100 ml of Prudhoe Bay (Alaska) crude oil/m2 of water surface (107 gal/acre, stabilized oil film 0.1 mm thick; a light to moderate oil spill) and pens in another group received a “low” treatment of 5 ml/m2 (5.3 gal/acre, stabilized oil film 0.005 mm thick; a very light oil spill). The third group of pens were untreated controls. Oil remained on the water for 48 hr, after which the troughs were drained, cleaned, and refilled with clean water. Water troughs in control pens were managed the same as the treatment pens. Ten control, nine low treatment, and ten high treatment nests were monitored for nest and egg temperature. A thermocouple was placed in the wood shavings and straw beneath the clutch and another thermocouple was placed in the air cell of one of the eggs according to a procedure slightly modified from that described by Caldwell and Cornwell (1975). Nests and eggs were probed the day before treatment and the probes were removed the day after the water troughs were drained and cleaned, a total of 4 days of monitoring. The probed egg was removed from the clutch at this time, candled, and destroyed. Temperature monitoring was controlled by a Trendscan 1000 data aquisition system, manufactured by Leeds & Northrup Company, North Wales, Pennsylvania (reference to trade names does not imply government endorsement of commercial products). The control unit scanned all probes at lo-min intervals and printed out the temperatures. After the water troughs were cleaned the females completed incubation and
TRANSFER
OF
CRUDE
OIL
TO
BIRD
EGGS
309
remained with their ducklings for 1 week. Eggs that did not hatch were opened after the female moved the ducklings out of the nest box. Clutches of unhatched eggs were opened after 30 days of incubation. Casual observations of the behavior of the breeding pairs were made before, during, and after exposure to oil to determine if oiling would cause changes in the male/female relationship or cause nest abandonment. After hatching, observations were made on the actions of the pair, particularly the female, toward the ducklings. TO confirm the transfer of oil to the eggs, five eggs from five randomly selected clutches within each group were collected several days after the 2-day exposure period and rinsed with hexane and acetone. The rinsings were pooled within each group, solvent volume was reduced, and the pooled rinsings were divided into aliphatic and aromatic fractions on Silicar columns. These six fractions were then reduced in volume to 0.1 ml each and injected on a capillary gas chromatograph/ mass spectrometer (30-m glass capillary, OV-101: Finnigan 3200 gc/ms). Hatching success and duckling survival were converted to percentages for each clutch and then transformed with an arcsine transformation for binomial proportions (Snedecor and Cochran, 1967, p. 327). The arcsine transformation was used because the range of percentages exceeded 30-70%. A one-way analysis of variance and t tests were performed on the transformed percentages. One-way analyses of variance were also used to analyze clutch size and the age of the embryos at the time of oil treatment. Egg and nest temperatures were analyzed with one-way analyses of variance and Duncan’s multiple range test. RESULTS Incrrhation
and
Nesting
Strcccss
Oil was easily detected by sight and smell on the feathers, feet, and bills of many of the birds in pens receiving the high treatment (100 ml/m”). When oil was obviously transferred to the eggs, the entire clutch was oiled and each egg appeared to be completely covered with the oil. It was difficult to detect oil by sight or smell on the bodies or eggs of birds in pens receiving the low treatment (5 ml/m?. The chemical analysis of the aliphatic fraction of the egg rinsings revealed a clear progression from high treatment to control in thl relative amounts of three aliphatic compounds found in crude oil (Fig. 1). Other aliphatic compounds were also detected but these three presented the clearest comparison between the three pooled rinsings. Nothing was found in the aromatic fraction of any of the rinsings. None of the oiled females abandoned their nests and no changes in the male/ female relationships were noticed. However, hatching success among the three groups was significantly different (F test, Table 1). The hatchability of eggs from the high treatment group was significantly less than that of the controls and that of the low treatment group. Hatchability of eggs from the low treatment group was less than that of the controls but the difference was not significant. Nine females in the high treatment group failed to hatch any eggs and six others hatched all their eggs. One female in the low treatment group failed to hatch any eggs and 12 hatched all their eggs. None of the females in the control group failed completely and 16 hatched all their eggs. This “all or nothing” characteristic of the females
310
PETER
H.
ALBERS
CONTROL
80 a
70 -
ii a
60 -
y
50-
F a
40 -
ii (L
30 20IO-
FIG.
fractions
1. The relative of the three
areas under the gas chromatograph pooled egg rinsings.
peaks
of three alkanes
found
in the aliphatic
exposed to 100 ml/m2 implies that 6 of them either avoided getting into the oiled water for the full 4%hr exposure period, or made very little contact with the water surface. Studies performed concurrently and subsequent to the present study have shown that female mallards do not enter oiled water as readily as unoiled water and that decreased hatching success is related to increased plumage contamination (Custer and Albers, in press: Albers, unpublished manuscript). A few eggs disappeared from some of the clutches during incubation. Some of TABLE THE
EFFECT
IN(.umI’ioN
ON EGG
HATCHABIL.ITY
TO A WATER
SOURCE
OF EXPOSING CONTAMINATED
1 BREEDING WITH
MALLARD PRUDHOE
DUCKS BAY
Percentage
DURING
CRUDE
of clutch
OIL
alive
Significance Treatment 1. Control 2. Low (5 ml/m”) 3. High (100 ml/m’)
Clutches 17 18 18
Eggs used 194 223 230
Percentage hatched 95.88 79.82 46.96
Mean percentage” 94.84 84.96 44.55
Overall” 0.000
Pairwise’ 1 x 2 = 0.060 1 x 3 = 0.001 2 x 3 = 0.014
” Mean of transformed percentages converted back to percentage (arcsine transformation nomial proportions). ” One-way analysis of variance, significant when P s 0.05. ’ f Test, significant for 1 x 2 and 1 x 3 when P s 0.015 and for 2 x 3 when P G 0.02.
for bi-
TRANSFER
OF
CRUDE
OIL
TO
BIRD
311
EGGS
these “missing eggs” were found on the ground or in the water trough. Most of those on the ground were broken. The number of missing eggs in the three groups (control = 3.09%, low = 5.38%, high = 3.04%) were compared by the same method used for egg hatchability to determine if this phenomenon was affected by the treatment; the number of missing eggs was not significantly different among groups. The survival of ducklings to 1 week of age was not significantly different among groups (Table 2). No gross behavioral or external physical abnormalities were noticed. The behavior of both sexes toward the young did not appear to differ among groups. The probing of an egg and the nest box of some of the pens did not adversly affect hatchability or the number of missing eggs. Seventy-six percent of the eggs in the 29 probed clutches hatched compared with a 69% hatch for the 24 unprobed clutches. Ten eggs were missing from the probed clutches and 15 eggs were missing from the unprobed clutches. The number of eggs laid, number of eggs used (eggs laid minus infertile and abnormal eggs), and age of embryo at the time of treatment for each experimental group were not significantly different among groups (F test, P > 0.05). The presence or absence of temperature probes in a nest was not related to the numbers of eggs laid or used. However, there appeared to be a difference in the age of the embryos at the time of treatment. A subsequent two-way analysis of variance revealed that the mean age difference (5 days vs 6 days) between nonprobed and probed nests was significant (P < 0.05). The water in pens with thermocouple probes was treated 1 day later than in pens without probes because temperatures were monitored for 24 hr before treatment. It is possible that this l-day delay could increase the hatchability of probed clutches by about l-6% (Albers, 1978). The hatchability of probed clutches in this study was 7% greater than that of unprobed clutches, but this difference, even if caused by the l-day delay, could not influence the treatment effect because almost the same number of nests were probed in each group (i.e., ten, nine, ten).
THE EFFECT ON DUCKLING SVRVIVAI INCUBATION TO A WATER SOURCE
TABLE 2 OF EXPOSING CONTAMINATED
BREEDING MALLARD DUCKS DURING WITH PRUDHOE BAY CRUDE OIL Percentage
of ducklings
surviving
Significance Treatment 1. Control 2. Low (5 mUmY) 3. High (100 ml/m’)
Clutches 17 I7 9
hw hatched 186 I78 108
Percentage survival 94.62 98.31 98.15
Mean Percentage” 94.82 96.35 96.88
Overall” 0.727
Pairwise’ I x 2 = 0.544 1 x 3 = 0.596 2 x 3 = 0.742
I’ Mean of transformed percentages converted back to percentage (arcsine transformation nomial proportions). b One-way analysis of variance, significant when P s 0.05. c t Test, significant for 1 x 2 and 1 x 3 when P s 0.015 and for 2 x 3 when P c 0.02.
for bi-
312
PETER
H.
ALBERS
Egg and Nest Temperatures
The incubation temperatures of the three experimental groups were compared for each day. Neither the daily means, minimums, maximums, ranges, or variances for egg or nest temperatures were significantly different (F test, P > 0.05) for any day. Pairwise comparisons also failed to reveal differences among groups (P > 0.05). The mean temperatures over the 4-day period were compared as an additional evaluation of temperature differences among experimental groups; differences were not significant (F test, P > 0.05). Day (0600- 1800 hr) and night temperatures were compared each day for each group to determine if darkness and the accompanying decrease in ambient temperature had any effect on incubating females exposed to oil. Day and night temperatures for eggs and nests were not significantly different (F test, P > 0.05). Because some females in the high and low treatment groups may have avoided the oil, the egg and nest temperatures of six females in the high treatment group that had hatching failure were compared with six females in the control group that hatched all of their eggs. Five of the six females in the high treatment group failed to hatch any of their eggs and the sixth hatched five of nine eggs. The same statistical analysis was used as for the three complete groups (ten, nine, ten) of females. Results of this analysis were identical to those comparing the complete groups. Egg and nest temperatures over the 4-day period were plotted and examined visually for differences in the temporal distribution of temperatures. No consistent differences were found. DISCUSSION
The detection by sight and smell of oil on incubating female mallards and the confirmation of the presence of oil on the eggs by chemical analysis (Fig. 1) show that aquatic birds can contaminate their own eggs with oil from oil-contaminated water. The actions of the oiled mallards indicated that subacutely oiled birds will resume incubation and will not act abnormally toward each other. Oiled birds of several wild species have also been seen incubating their eggs, but either the complete incubation period was not observed or the observations were brief and only involved a few birds (Rittinghaus, 1956; Birkhead et al., 1973; King and Lefever, 1979). The exposure of incubating birds to petroleum can have a devastating effect on egg hatchability, particularly when the amount of crude oil on the water is at least 100 ml/m2. A heavy oil spill could put lo-20 times this amount of crude oil on the water. In the present study the 100 ml/m2 of crude oil was sufficient for oiled females, through periodic turning of the eggs, to completely oil all the eggs and cause a total hatching failure. Small amounts of oil on water, approximately 5 ml/m”, probably can cause a reduction in egg hatchability, but the reduction may not exceed natural variation often enough to be meaningful. However, a small increase in the oil present, say 10 ml/m2 (10.6 gal/acre), may be sufficient to cause a meaningful reduction. Crude and refined oils have variable toxicities and different species of birds are affected differently by oil, but the amounts of Prudhoe Bay crude oil used in this study can serve as a general guide for estimating the impact of petroleum on incubating birds.
TRANSFER
OF
CRUDE
OIL
TO
BIRD
EGGS
313
Oil contamination during incubation does not appear to affect the survival of precocial young during the first week. Neither the ducklings nor the previously oiled adults displayed unusual behavior toward each other that would indicate a delayed effect of the oil. Observations of posthatching behavior do not include the ten birds that were oiled enough to lose their entire clutch; I do not know how these birds would react to ducklings. Gross behavioral effects on ducklings during the first day after hatch were also absent in other egg oiling studies (Albers, 1977, 1978; Szaro and Albers, 1977; Szaro et al., 1978). However, my observations of bird behavior, both pre- and posthatch, were very general and based primarily on comparisons among groups. The oil exposure may have modified the behavior of adults or young in ways that can be detected by rigorous testing procedures. Exposure to crude oil did not affect the incubation temperature of the female mallard ducks. This finding is in contrast to the reports of abnormal incubation and reduced hatching success for ring doves and herring gulls that were thought to be caused by PCBs and organochlorine compounds (Peakall and Peakall, 1973; Fox et al., 1978). ACKNOWLEDGMENTS I thank Allen Biller and Jeffrey Schnebelen for their chemical analysis. and William C. Eastin and Donald manuscript.
help during the study, Martha Gay H. White for a preliminary review
for the of this
REFERENCES Albers, P. H. (1977). Effects of external applications of fuel oil on hatchability of mallard eggs. 1)~ “Fate and Effects of Petroleum Hydrocarbons in Marine Ecosystems and Organisms” (D. A. Wolfe, Ed.), pp. 158- 163. Pergamon, New York. Albers. P. H. (1978). The effects of petroleum on different stages of incubation in bird eggs. B/I//. En~~irorr. Conturn. To.rico/. 19. 624-630. Albers, P. H., and Szaro, R. C. (1978). Effects of No. 2 fuel oil on common eider eggs. Mtrr. Polllrt. Bull. 9. l38- 139. Birkhead. T. R.. Lloyd, C., and Corkhill. P. (1973). Oiled seabirds successfully cleaning their plumage. Brit. Birds 66, 535~537. Caldwell. P. J., and Cornwell, G. W. (1975). Incubation behavior and temperatures of the mallard duck. A///i 4, 706-731. Coon, N. C., Albers. P. H., and Szaro, R. C. ( 1979). No. 2 fuel oil decreases embryonic survival of great black-backed gulls. B///I. Enr*irorr. Cr~nttrm. 7i,\-icd. 21, 1522 156. Custer, T. W.. and Albers. P. H. (1980). Response of captive breeding mallards to oiled water. J. Wild/. Mtrntrgr., in press. Fox, G. A., Gilman. A. P., Peakall. D. B.. and Anderka. F. W. (1978). Behavioral abnormalities of nesting Lake Ontario herring gulls. J. Wild. Mancrgc,. 42. 477~483. Hartung, R. (1965). Some effects of oiling on reproduction of ducks. .I. Wild/. Manugc~. 29, 872-874. Keith, J. A. (1966). Reproduction in a population of herring gulls (Lorrrs urgentnrlrs) contaminated by DDT. J. Appl. Eccd. (Suppl.). 3, 57~70. King, K. A., and Lefever. C. A. ( 1979). Effects of oil transferred from incubating gulls to their eggs. Mar. Pollrtf. Bull.. 10, 319-321. McGill. P. A., and Richmond, M. E. (1979). Hatching success of great black-backed gull eggs treated with oil. Bird Brrndi!rg 50, 108~ 113. Peakall, D. B., and Peakall. M. L. (1973). Effect of a polychlorinated biphenyl on the reproduction of artificially and naturally incubated dove eggs. J. Appl. Ecd. 10, 863-868. Rittinghaus, H. (1956). Etwas uber die indirekte Verbreitung der Glpest in einem Seevogelschutzegebiete. Umitlrol. Mir. 8, 43346. Snedecor. G. W., and Cochran, W. G. (1967). “Statistical Methods,” 6th ed. Iowa State Univ. Press, Ames, Iowa.
314 Szaro,
PETER
R. C. (1979). To.rico/.
Szaro,
22,
Bunker
C fuel
oil reduces
H.
ALBERS
mallard
egg hatchability.
BJ.
Em~iron.
Contcrnt.
731-732.
R. C.. and Albers, P. H. (1977). Effects of external applications of No. 2 fuel oil on common eider eggs. In “Fate and Effects of Petroleum Hydrocarbons in Marine Ecosystems and Organisms” (D. A. Wolfe, Ed.), pp. 164-167. Pergamon, New York. Szaro, R. C., Albers, P. H., and Coon,N. C. (1978). Petroleum: effects on mallard egg hatchability. J. Wild/. Munage. 42, 404-406. White, D. H., King, K, A., and Coon, N. C. (1979). Effects of No. 2 fuel oil on hatchability of marine and estuarine bird eggs. Bul/. Enthm. Contam. 7’micol. 21, 7- 10.
RESEARCH
Transfer
22. 307-314 (1980)
of Crude
Oil from Contaminated Bird Eggs
Water to
PETERH. ALBERS
Pairs of breeding mallard ducks were exposed to oiled water for 2 days during the first week of incubation. Hatching success of ducks exposed to 100 ml of Prudhoe Bay crude oil per square meter of water surface was significantly less than that of controls. Hatching success of ducks exposed to 5 ml of crude oil per square meter of water surface was less than that of controls but the difference was not significant. The presence of oil on the eggs of ducks exposed to oiled water was confirmed by chemical analysis. Thermocouple probes were used to monitor the egg and nest temperatures of some of the ducks in each of the three groups. Incubation temperatures of oiled females were not significantly different from those of the controls. The incubation behavior of females exposed to oiled water and the first-week survival of their ducklings was not affected by the oil.
INTRODUCTION
Oil spills frequently result in the oiling of large numbers of aquatic birds. If the spill occurs during the spring, breeding birds are affected and oil may be transferred to the eggs on the feathers or feet of the incubating adults (Rittinghaus, 1956; Birkhead et al.. 1973). Hartung (1965) and King and Lefever (1979) demonstrated that oil applied to the breast feathers of incubating mallards and laughing gulls (Latxs utricilla) could be transferred to the eggs. Severe reductions in egg hatchability were caused by the transferred oil in each of these instances. Crude and refined oils are very toxic to bird embryos, particularly during the first 10 days of incubation. Applications of Southern Louisiana and Kuwait crude oils, No. 2 fuel oil, and Bunker C fuel oil on the egg shell in quantities as small as l-5 liters have significantly decreased the hatchability of artificially incubated mallard (Anus plutyrhynchos) and great black-backed gull (Lurns marks) eggs (Albers, 1977, 1978: Szaro et N/., 1978; Coon ef al., 1979; Szaro, 1979). Applications of 20 ~1 of No. 2 fuel oil on the naturally incubated eggs of common eiders (Somuteriu molfissimu). Louisiana herons (Hylrunussu tricolor), laughing gulls (Laws utriciflu), great black-backed gulls, and sandwich terns (Sterna sundvicensis) also significantly decreased egg hatchability (Albers and Szaro, 1978; White et al., 1979; Coon et al., 1979: McGill and Richmond, 1979). Although oil can be transferred from feathers to eggs (Hartung, 1965: King and Lefever, 1979), it has not been demonstrated experimentally that an incubating bird confronted with oil-contaminated water will enter the water, become oiled, and then transfer that oil to the eggs. Furthermore, the effects of a sublethal exposure to oil on incubation behavior are unknown. Keith (1966) first proposed that environmental contaminants, such as DDT, may affect hatchability through their effect on incubation behavior. Peakall and Peakall (1973) showed that the 307 0013-935
l/80/040307-08$02.00/O
Copyright fe 1980 by Academic Press. Inc. All rights of reproduction in any form recerved.
308
PETER
H.
ALBERS
mean temperature was lower and the variation in nest temperature over a 24-hr period was greater for ring doves (Streptopelia risoria) maintained on a diet containing a PCB (Aroclor 1254) than for control birds. Hatching success for the PCB-fed doves was less than for the controls. Unsuccessful nests of herring gull (Lams argentatus) had greater daily variation in nest air temperatures and poorer nest attentiveness by the incubating bird than successful nests (Fox et al., 1978). Organochlorine compounds and PCBs were thought to be responsible for this abnormal incubation behavior. The assumption that an incubating bird can oil itself from contaminated water and transfer the oil to the eggs in amounts sufficient to significantly reduce egg hatchability was tested in the present study. In addition, the effect of sublethal oiling on several aspects of incubation behavior was evaluated. METHODS
AND MATERIALS
Two-year-old mallard ducks were paired and placed in 54 outdoor pens at the Patuxent Wildlife Research Center, Laurel, Maryland, in early February 1978. Each pen measured 4.6 m long by 4.6 m wide by 1.8 m high and contained a water trough 1.2 m long by 0.9 m wide by 0.3 m deep, a cylindrical wire and tarpaper nest box, a feeder, and an electrical outlet. Each nest box contained a layer of straw on top of a layer of wood shavings. The pens were randomly divided into three groups of 18 pens each. The ducks were fed commercial duck breeder pellets throughout the experiment. The completed clutches of eggs were candled every other day to monitor embryonic development. At a convenient time during the first 10 days of incubation, usually Days 5 or 6, the infertile eggs and eggs with retarded development were removed and the water in the troughs was treated with crude oil. Pens in one group received a “high” treatment of 100 ml of Prudhoe Bay (Alaska) crude oil/m2 of water surface (107 gal/acre, stabilized oil film 0.1 mm thick; a light to moderate oil spill) and pens in another group received a “low” treatment of 5 ml/m2 (5.3 gal/acre, stabilized oil film 0.005 mm thick; a very light oil spill). The third group of pens were untreated controls. Oil remained on the water for 48 hr, after which the troughs were drained, cleaned, and refilled with clean water. Water troughs in control pens were managed the same as the treatment pens. Ten control, nine low treatment, and ten high treatment nests were monitored for nest and egg temperature. A thermocouple was placed in the wood shavings and straw beneath the clutch and another thermocouple was placed in the air cell of one of the eggs according to a procedure slightly modified from that described by Caldwell and Cornwell (1975). Nests and eggs were probed the day before treatment and the probes were removed the day after the water troughs were drained and cleaned, a total of 4 days of monitoring. The probed egg was removed from the clutch at this time, candled, and destroyed. Temperature monitoring was controlled by a Trendscan 1000 data aquisition system, manufactured by Leeds & Northrup Company, North Wales, Pennsylvania (reference to trade names does not imply government endorsement of commercial products). The control unit scanned all probes at lo-min intervals and printed out the temperatures. After the water troughs were cleaned the females completed incubation and
TRANSFER
OF
CRUDE
OIL
TO
BIRD
EGGS
309
remained with their ducklings for 1 week. Eggs that did not hatch were opened after the female moved the ducklings out of the nest box. Clutches of unhatched eggs were opened after 30 days of incubation. Casual observations of the behavior of the breeding pairs were made before, during, and after exposure to oil to determine if oiling would cause changes in the male/female relationship or cause nest abandonment. After hatching, observations were made on the actions of the pair, particularly the female, toward the ducklings. TO confirm the transfer of oil to the eggs, five eggs from five randomly selected clutches within each group were collected several days after the 2-day exposure period and rinsed with hexane and acetone. The rinsings were pooled within each group, solvent volume was reduced, and the pooled rinsings were divided into aliphatic and aromatic fractions on Silicar columns. These six fractions were then reduced in volume to 0.1 ml each and injected on a capillary gas chromatograph/ mass spectrometer (30-m glass capillary, OV-101: Finnigan 3200 gc/ms). Hatching success and duckling survival were converted to percentages for each clutch and then transformed with an arcsine transformation for binomial proportions (Snedecor and Cochran, 1967, p. 327). The arcsine transformation was used because the range of percentages exceeded 30-70%. A one-way analysis of variance and t tests were performed on the transformed percentages. One-way analyses of variance were also used to analyze clutch size and the age of the embryos at the time of oil treatment. Egg and nest temperatures were analyzed with one-way analyses of variance and Duncan’s multiple range test. RESULTS Incrrhation
and
Nesting
Strcccss
Oil was easily detected by sight and smell on the feathers, feet, and bills of many of the birds in pens receiving the high treatment (100 ml/m”). When oil was obviously transferred to the eggs, the entire clutch was oiled and each egg appeared to be completely covered with the oil. It was difficult to detect oil by sight or smell on the bodies or eggs of birds in pens receiving the low treatment (5 ml/m?. The chemical analysis of the aliphatic fraction of the egg rinsings revealed a clear progression from high treatment to control in thl relative amounts of three aliphatic compounds found in crude oil (Fig. 1). Other aliphatic compounds were also detected but these three presented the clearest comparison between the three pooled rinsings. Nothing was found in the aromatic fraction of any of the rinsings. None of the oiled females abandoned their nests and no changes in the male/ female relationships were noticed. However, hatching success among the three groups was significantly different (F test, Table 1). The hatchability of eggs from the high treatment group was significantly less than that of the controls and that of the low treatment group. Hatchability of eggs from the low treatment group was less than that of the controls but the difference was not significant. Nine females in the high treatment group failed to hatch any eggs and six others hatched all their eggs. One female in the low treatment group failed to hatch any eggs and 12 hatched all their eggs. None of the females in the control group failed completely and 16 hatched all their eggs. This “all or nothing” characteristic of the females
310
PETER
H.
ALBERS
CONTROL
80 a
70 -
ii a
60 -
y
50-
F a
40 -
ii (L
30 20IO-
FIG.
fractions
1. The relative of the three
areas under the gas chromatograph pooled egg rinsings.
peaks
of three alkanes
found
in the aliphatic
exposed to 100 ml/m2 implies that 6 of them either avoided getting into the oiled water for the full 4%hr exposure period, or made very little contact with the water surface. Studies performed concurrently and subsequent to the present study have shown that female mallards do not enter oiled water as readily as unoiled water and that decreased hatching success is related to increased plumage contamination (Custer and Albers, in press: Albers, unpublished manuscript). A few eggs disappeared from some of the clutches during incubation. Some of TABLE THE
EFFECT
IN(.umI’ioN
ON EGG
HATCHABIL.ITY
TO A WATER
SOURCE
OF EXPOSING CONTAMINATED
1 BREEDING WITH
MALLARD PRUDHOE
DUCKS BAY
Percentage
DURING
CRUDE
of clutch
OIL
alive
Significance Treatment 1. Control 2. Low (5 ml/m”) 3. High (100 ml/m’)
Clutches 17 18 18
Eggs used 194 223 230
Percentage hatched 95.88 79.82 46.96
Mean percentage” 94.84 84.96 44.55
Overall” 0.000
Pairwise’ 1 x 2 = 0.060 1 x 3 = 0.001 2 x 3 = 0.014
” Mean of transformed percentages converted back to percentage (arcsine transformation nomial proportions). ” One-way analysis of variance, significant when P s 0.05. ’ f Test, significant for 1 x 2 and 1 x 3 when P s 0.015 and for 2 x 3 when P G 0.02.
for bi-
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EGGS
these “missing eggs” were found on the ground or in the water trough. Most of those on the ground were broken. The number of missing eggs in the three groups (control = 3.09%, low = 5.38%, high = 3.04%) were compared by the same method used for egg hatchability to determine if this phenomenon was affected by the treatment; the number of missing eggs was not significantly different among groups. The survival of ducklings to 1 week of age was not significantly different among groups (Table 2). No gross behavioral or external physical abnormalities were noticed. The behavior of both sexes toward the young did not appear to differ among groups. The probing of an egg and the nest box of some of the pens did not adversly affect hatchability or the number of missing eggs. Seventy-six percent of the eggs in the 29 probed clutches hatched compared with a 69% hatch for the 24 unprobed clutches. Ten eggs were missing from the probed clutches and 15 eggs were missing from the unprobed clutches. The number of eggs laid, number of eggs used (eggs laid minus infertile and abnormal eggs), and age of embryo at the time of treatment for each experimental group were not significantly different among groups (F test, P > 0.05). The presence or absence of temperature probes in a nest was not related to the numbers of eggs laid or used. However, there appeared to be a difference in the age of the embryos at the time of treatment. A subsequent two-way analysis of variance revealed that the mean age difference (5 days vs 6 days) between nonprobed and probed nests was significant (P < 0.05). The water in pens with thermocouple probes was treated 1 day later than in pens without probes because temperatures were monitored for 24 hr before treatment. It is possible that this l-day delay could increase the hatchability of probed clutches by about l-6% (Albers, 1978). The hatchability of probed clutches in this study was 7% greater than that of unprobed clutches, but this difference, even if caused by the l-day delay, could not influence the treatment effect because almost the same number of nests were probed in each group (i.e., ten, nine, ten).
THE EFFECT ON DUCKLING SVRVIVAI INCUBATION TO A WATER SOURCE
TABLE 2 OF EXPOSING CONTAMINATED
BREEDING MALLARD DUCKS DURING WITH PRUDHOE BAY CRUDE OIL Percentage
of ducklings
surviving
Significance Treatment 1. Control 2. Low (5 mUmY) 3. High (100 ml/m’)
Clutches 17 I7 9
hw hatched 186 I78 108
Percentage survival 94.62 98.31 98.15
Mean Percentage” 94.82 96.35 96.88
Overall” 0.727
Pairwise’ I x 2 = 0.544 1 x 3 = 0.596 2 x 3 = 0.742
I’ Mean of transformed percentages converted back to percentage (arcsine transformation nomial proportions). b One-way analysis of variance, significant when P s 0.05. c t Test, significant for 1 x 2 and 1 x 3 when P s 0.015 and for 2 x 3 when P c 0.02.
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Egg and Nest Temperatures
The incubation temperatures of the three experimental groups were compared for each day. Neither the daily means, minimums, maximums, ranges, or variances for egg or nest temperatures were significantly different (F test, P > 0.05) for any day. Pairwise comparisons also failed to reveal differences among groups (P > 0.05). The mean temperatures over the 4-day period were compared as an additional evaluation of temperature differences among experimental groups; differences were not significant (F test, P > 0.05). Day (0600- 1800 hr) and night temperatures were compared each day for each group to determine if darkness and the accompanying decrease in ambient temperature had any effect on incubating females exposed to oil. Day and night temperatures for eggs and nests were not significantly different (F test, P > 0.05). Because some females in the high and low treatment groups may have avoided the oil, the egg and nest temperatures of six females in the high treatment group that had hatching failure were compared with six females in the control group that hatched all of their eggs. Five of the six females in the high treatment group failed to hatch any of their eggs and the sixth hatched five of nine eggs. The same statistical analysis was used as for the three complete groups (ten, nine, ten) of females. Results of this analysis were identical to those comparing the complete groups. Egg and nest temperatures over the 4-day period were plotted and examined visually for differences in the temporal distribution of temperatures. No consistent differences were found. DISCUSSION
The detection by sight and smell of oil on incubating female mallards and the confirmation of the presence of oil on the eggs by chemical analysis (Fig. 1) show that aquatic birds can contaminate their own eggs with oil from oil-contaminated water. The actions of the oiled mallards indicated that subacutely oiled birds will resume incubation and will not act abnormally toward each other. Oiled birds of several wild species have also been seen incubating their eggs, but either the complete incubation period was not observed or the observations were brief and only involved a few birds (Rittinghaus, 1956; Birkhead et al., 1973; King and Lefever, 1979). The exposure of incubating birds to petroleum can have a devastating effect on egg hatchability, particularly when the amount of crude oil on the water is at least 100 ml/m2. A heavy oil spill could put lo-20 times this amount of crude oil on the water. In the present study the 100 ml/m2 of crude oil was sufficient for oiled females, through periodic turning of the eggs, to completely oil all the eggs and cause a total hatching failure. Small amounts of oil on water, approximately 5 ml/m”, probably can cause a reduction in egg hatchability, but the reduction may not exceed natural variation often enough to be meaningful. However, a small increase in the oil present, say 10 ml/m2 (10.6 gal/acre), may be sufficient to cause a meaningful reduction. Crude and refined oils have variable toxicities and different species of birds are affected differently by oil, but the amounts of Prudhoe Bay crude oil used in this study can serve as a general guide for estimating the impact of petroleum on incubating birds.
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Oil contamination during incubation does not appear to affect the survival of precocial young during the first week. Neither the ducklings nor the previously oiled adults displayed unusual behavior toward each other that would indicate a delayed effect of the oil. Observations of posthatching behavior do not include the ten birds that were oiled enough to lose their entire clutch; I do not know how these birds would react to ducklings. Gross behavioral effects on ducklings during the first day after hatch were also absent in other egg oiling studies (Albers, 1977, 1978; Szaro and Albers, 1977; Szaro et al., 1978). However, my observations of bird behavior, both pre- and posthatch, were very general and based primarily on comparisons among groups. The oil exposure may have modified the behavior of adults or young in ways that can be detected by rigorous testing procedures. Exposure to crude oil did not affect the incubation temperature of the female mallard ducks. This finding is in contrast to the reports of abnormal incubation and reduced hatching success for ring doves and herring gulls that were thought to be caused by PCBs and organochlorine compounds (Peakall and Peakall, 1973; Fox et al., 1978). ACKNOWLEDGMENTS I thank Allen Biller and Jeffrey Schnebelen for their chemical analysis. and William C. Eastin and Donald manuscript.
help during the study, Martha Gay H. White for a preliminary review
for the of this
REFERENCES Albers, P. H. (1977). Effects of external applications of fuel oil on hatchability of mallard eggs. 1)~ “Fate and Effects of Petroleum Hydrocarbons in Marine Ecosystems and Organisms” (D. A. Wolfe, Ed.), pp. 158- 163. Pergamon, New York. Albers. P. H. (1978). The effects of petroleum on different stages of incubation in bird eggs. B/I//. En~~irorr. Conturn. To.rico/. 19. 624-630. Albers, P. H., and Szaro, R. C. (1978). Effects of No. 2 fuel oil on common eider eggs. Mtrr. Polllrt. Bull. 9. l38- 139. Birkhead. T. R.. Lloyd, C., and Corkhill. P. (1973). Oiled seabirds successfully cleaning their plumage. Brit. Birds 66, 535~537. Caldwell. P. J., and Cornwell, G. W. (1975). Incubation behavior and temperatures of the mallard duck. A///i 4, 706-731. Coon, N. C., Albers. P. H., and Szaro, R. C. ( 1979). No. 2 fuel oil decreases embryonic survival of great black-backed gulls. B///I. Enr*irorr. Cr~nttrm. 7i,\-icd. 21, 1522 156. Custer, T. W.. and Albers. P. H. (1980). Response of captive breeding mallards to oiled water. J. Wild/. Mtrntrgr., in press. Fox, G. A., Gilman. A. P., Peakall. D. B.. and Anderka. F. W. (1978). Behavioral abnormalities of nesting Lake Ontario herring gulls. J. Wild. Mancrgc,. 42. 477~483. Hartung, R. (1965). Some effects of oiling on reproduction of ducks. .I. Wild/. Manugc~. 29, 872-874. Keith, J. A. (1966). Reproduction in a population of herring gulls (Lorrrs urgentnrlrs) contaminated by DDT. J. Appl. Eccd. (Suppl.). 3, 57~70. King, K. A., and Lefever. C. A. ( 1979). Effects of oil transferred from incubating gulls to their eggs. Mar. Pollrtf. Bull.. 10, 319-321. McGill. P. A., and Richmond, M. E. (1979). Hatching success of great black-backed gull eggs treated with oil. Bird Brrndi!rg 50, 108~ 113. Peakall, D. B., and Peakall. M. L. (1973). Effect of a polychlorinated biphenyl on the reproduction of artificially and naturally incubated dove eggs. J. Appl. Ecd. 10, 863-868. Rittinghaus, H. (1956). Etwas uber die indirekte Verbreitung der Glpest in einem Seevogelschutzegebiete. Umitlrol. Mir. 8, 43346. Snedecor. G. W., and Cochran, W. G. (1967). “Statistical Methods,” 6th ed. Iowa State Univ. Press, Ames, Iowa.
314 Szaro,
PETER
R. C. (1979). To.rico/.
Szaro,
22,
Bunker
C fuel
oil reduces
H.
ALBERS
mallard
egg hatchability.
BJ.
Em~iron.
Contcrnt.
731-732.
R. C.. and Albers, P. H. (1977). Effects of external applications of No. 2 fuel oil on common eider eggs. In “Fate and Effects of Petroleum Hydrocarbons in Marine Ecosystems and Organisms” (D. A. Wolfe, Ed.), pp. 164-167. Pergamon, New York. Szaro, R. C., Albers, P. H., and Coon,N. C. (1978). Petroleum: effects on mallard egg hatchability. J. Wild/. Munage. 42, 404-406. White, D. H., King, K, A., and Coon, N. C. (1979). Effects of No. 2 fuel oil on hatchability of marine and estuarine bird eggs. Bul/. Enthm. Contam. 7’micol. 21, 7- 10.